Valve Timing Adjusting Device

ABSTRACT

A valve timing adjusting device includes a first rotor rotating integrally with a crankshaft; a second rotor secured integrally with an intake or exhaust camshaft; a first hole formed passing through radially to a shoe formed inside the first rotor; a second hole formed through the shoe, intersecting the first hole; a coil spring pressing a lock pin received in the first hole to thereby engage the lock pin into a concavity formed on the outer peripheral surface of the second rotor; and a shaft inserted into the second hole in order to prevent the coil spring from dashing out.

TECHNICAL FIELD

The present invention relates to a valve timing adjusting devicecontrolling the open and close timing of an intake valve or exhaustvalve of an internal combustion engine such as an engine (hereinafterreferred to as an “engine”).

BACKGROUND ART

A conventional valve timing adjusting device includes a first rotor thatintegrally secures a case inside having a plurality of projecting shoesand forming an oil pressure chamber between those shoes, a front cover,and a rear cover, both covering those oil pressure chambers, and thatrotates integrally with a crank shaft; and a second rotor that has aplurality of vanes each dividing each of those oil pressure chambersinto an advanced-side oil pressure chamber and a retarded-side oilpressure chamber, can relatively rotate by a predetermined angle withinthe first rotor, and is secured integrally with an intake or exhaustcamshaft, wherein the hydraulic pressure of an oil pump assuming chargeof supplying oil to a sliding section of an engine is supplied andexhausted, and the hydraulic pressure controls the relative position ofthe second rotor with respect to the first rotor.

In the above-mentioned structure, in the absence of hydraulic forcewithin the oil pressure chambers when the engine is started, the shoesof the first rotor and the vanes of the second rotor repeatedly abutagainst and separate from each other, thereby producing slapping sounds.For this reason, the production of slapping sounds is suppressed byproviding a first hole passing through radially to the shoe; pressing alock pin received in the first hole with a coil spring inserted in thehole, to engage the lock pin into a concavity provided on the outerperipheral surface of the second rotor when the second rotor assumed themost retarded position, for example; and thereby, locking the relativeposition between the first rotor and the second rotor. Note that thelock pin is moved in a releasing direction by hydraulic force againsturging force induced by the coil spring. When the lock pin is moved, theback pressure behind the lock pin is exhausted outside.

In such a case, a lock structure for preventing the coil spring fromdashing or jumping out is required. Conventionally, the following fourtypes are provided for the lock structure.

The first lock structure, when the coil spring is locked against dashingout movement with a stopper, which is a cylinder member, inserted in alock pin receiving hole from outside radially to the device, secures thestopper with a shaft inserted along the direction orthogonal to the lockpin receiving hole. However, according to the structure, the diameter ofa shaft receiving hole formed along the direction orthogonal to the lockpin receiving hole becomes small. This requires the shaft receiving holeto be specially machined. For this reason, the number of productionprocesses increases, which incurs an increase in cost. Moreover, thestructure needs two parts, the stopper and the shaft to lock the coilspring so as not to dash out.

The second one, as shown in Patent Document 1, when the coil spring islocked so as not to dash out by inserting a plate-shaped stopper into agroove formed along the direction orthogonal to the lock pin receivinghole, requires high machining accuracy for machining the groove.Besides, the structure is difficult in assembly because the plate-shapedstopper is inserted into the groove after the insertion of the lock pinand the coil spring into the receiving hole from outside radially to thedevice.

The third lock structure, in which the coil spring is locked againstdashing out movement by a stopper press-fitted into the lock pinreceiving hole from outside radially to the device, might dislodge thestopper therefrom because of centrifugal force in a high revolution areaand might dislodge the stopper due to looseness from vibrations.Furthermore, the structure needs production control for the press fitforce and the press fit size of the stopper.

The fourth structure, as shown in Patent Document 2, where the coilspring is locked for preventing its dashing-out movement by means of thewall surface of a groove provided on a case, is difficult in assemblybecause the coil spring has to be inserted, together with the lock pin,into a retracting groove under compressed conditions.

Patent Document 1: JP-A-11-101107

Patent Document 2: JP-A-2005-002952

The conventional valve timing adjusting devices are arranged asmentioned above. Accordingly, various lock structures for locking thecoil spring so as not to dash out are used for the device; however,those lock structures have shortcomings: need for high machiningaccuracy, difficulty in assembly, the dislodgement of the stopper due tocentrifugal force in a high revolution area and the dislodgement of thestopper caused by looseness from vibrations, and necessity forproduction control for the press-fit force and the press-fit size of thestopper, respectively.

The present invention has been made to solve the above-mentionedproblems. An object of the present invention is to provide a valvetiming adjusting device loosening working accuracy requirements,improving workability and assembling, and employing a locking memberwith a simple shape to be easily manufactured.

DISCLOSURE OF THE INVENTION

The valve timing adjusting device according to the present inventionincludes a first rotor that integrally secure a case inside having aplurality of projecting shoes and forming an oil pressure chamberbetween those shoes, a front cover, and a rear cover, both coveringthose oil pressure chambers, and that rotates integrally with a crankshaft; a second rotor that has a plurality of vanes each dividing eachof the oil pressure chambers into an advanced-side oil pressure chamberand a retarded-side oil pressure chamber, is able to relatively rotateby a predetermined angle within the first rotor, and is securedintegrally with an intake or exhaust camshaft; a hydraulic pressuresupply and exhaust means capable of supplying working fluid to andexhausting it from the advanced-side oil pressure chambers and theretarded-side oil pressure chambers; a first hole passing through theshoe radially to the device; a second hole formed through the shoe,intersecting the first hole; a coil spring pressing a lock pin receivedin the first hole to thereby engage the lock pin into a concavityprovided on an outer peripheral surface of the second rotor; and a shaftinserted into the second hole in order to prevent the coil spring fromdashing out.

According to the present invention, it is arranged such that the coilspring is locked against dashing out movement by the shaft inserted intothe second hole provided intersecting the first hole receiving the lockpin and the coil spring. This enables the hole where the shaft isinserted to have a size near to the diameter of the lock pin receivinghole, permits the hole where the shaft is inserted to be died, andeliminates the requirement of machining the hole by machining. As aresult, this provides a valve timing adjusting device excellent informing. Further, the hole having a larger diameter to be inserted bythe shaft can achieve loosened dimensional accuracy requirements toimprove workability and assembling, and further permits the shaft tohave a simple shape of a virtually cylindrical configuration, therebyfacilitating the manufacture of the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an internal structure of a valve timingadjusting device according to the first embodiment of the presentinvention, and is a longitudinal sectional view when a second rotor islocated at the most retarded position.

FIG. 2 is a transverse sectional view along the line A-A of FIG. 1.

FIG. 3 is a longitudinal sectional view along the line B-B of FIG. 2.

FIG. 4 is a longitudinal sectional view of the valve timing adjustingdevice when the second rotor is located at the most advanced position.

FIG. 5 is an enlarged transverse sectional view of essential partsshowing a state where the second rotor is locked.

FIG. 6 is an enlarged longitudinal sectional view of essential partsshowing a state where the second rotor is locked.

FIG. 7 is an enlarged transverse sectional view of essential partsshowing a state where the second rotor is lock-released.

FIG. 8 is an enlarged longitudinal sectional view of essential partsshowing a state where the second rotor is lock-released.

FIG. 9 is an enlarged transverse sectional view of essential partsshowing a state where a lock pin and a coil spring are assembled.

FIG. 10 is an enlarged transverse sectional view of essential partsexplaining why the second rotor cannot rotate relatively to the firstrotor.

FIG. 11 is an enlarged longitudinal sectional view of essential partsexplaining why the second rotor cannot be assembled to the first rotor.

FIG. 12 is an enlarged longitudinal sectional view of essential partsshowing a state where a cylinder shaped shaft and a stepped cylindershaped lock pin are assembled.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will now be described withreference to the accompanying drawings in order to explain the presentinvention in more detail.

First Embodiment

The drawings are views of the internal structure of a valve timingadjusting device according to the first embodiment of the presentinvention; FIG. 1 is a longitudinal sectional view of the valve timingadjusting device when a second rotor is located at the most retardedposition; FIG. 2 is a transverse sectional view along the line A-A ofFIG. 1; FIG. 3 is a longitudinal sectional view along the line B-B ofFIG. 2; and FIG. 4 is a longitudinal sectional view of the valve timingadjusting device when the second rotor is located at the most advancedposition.

As shown in FIG. 1 to FIG. 4, the valve timing adjusting device 1according to the first embodiment is generally composed of a first rotor1 rotating synchronously with a crankshaft (not shown) of an engine (notshown) through a chain (not shown) and a second rotor 3 provided withinthe first rotor 1 and secured integrally with the end face of an intakeor exhaust camshaft (hereinafter referred to as a camshaft).

The first rotor 1 is generally composed of a case 4 that has outside asprocket 4 a receiving a rotational driving force of the crankshaft (notshown) and has inside a plurality of shoes 4 b inwardly projectingradially to the device, a front cover 5, and a rear cover 6, bothcovering the internal space of the case 4. Those three components areintegrally fastened to each other with a bolt 7.

The second rotor 3 is composed of a boss 10 a fastened integrally withthe end face of the camshaft 2 through a washer 8 with a bolt 9, and arotor 10 having a plurality of vanes 10 b outwardly projecting, radiallyto the device, from the outer periphery of the boss 10 a. The vanes 10 bof the rotor 10 partitions a plurality of internal spaces formed by theshoes 4 b of the case 4 into an advanced-side oil pressure chamber 11supplied with hydraulic pressure when the rotor 10 is relatively rotatedin the direction of the advanced-side with respect to the first rotor 1and a retarded-side oil pressure chamber 12 supplied with hydraulicpressure when the rotor 10 is relatively rotated in the retarded-sidedirection with respect to the first rotor. The advanced-side oilpressure chambers communicate with advanced-side oil passages 13supplying hydraulic pressure thereto and exhausting it therefrom, andthe retarded-side oil pressure chambers communicate with retarded-sideoil passages 14 supplying hydraulic pressure thereto and exhausting ittherefrom.

A receiving hole (first hole) 15 is formed in the shoe 4 b of the case 4a, and passes through the shoe radially to the device. In the receivinghole 15, a nearly cylindrical lock pin 16 that is reciprocally slidableradially to the device is inserted from outside radially thereto anddisposed therein. Moreover, a nearly cylindrical hole (second hole) 4b-1 is formed in the shoe 4 b in the direction (axially to the rotor 10)orthogonal to the receiving hole 15, and a nearly cylindrical shaft 17inserted into the hole 4 b-1 locks the rear end of a coil spring 18inserted into the receiving hole 15 so as to press the lock pin 16 andthe rear end of the lock pin 16.

The diameter of the shaft 17 is designed smaller than the diameter ofthe receiving hole 15 of the lock pin 16, and further, smaller than thediameter of the coil spring 18. In addition, when the shaft 17 is formedwith a D-shaped cross section, the position of the bearing surfacehaving the D-shaped cross section can be changed either opposed ornot-opposed to the coil spring 18, depending on the assembly directionof the shaft 17.

When the relative position of the rotor 10 with respect to the case 4 isat the most retarded position, an engaging concavity 19 is formed on theouter periphery of the boss 10 a of the rotor 10, and engaged with thetip of the-lock pin 16 that is inwardly advanced radially to the deviceby urging force from the coil spring 18. Besides, the engaging concavity19 communicates with a release oil passage 20.

The operation will now be described below.

First, when the relative position of the rotor 10 with respect to thecase 4 is located at the most retarded position shown in from FIG. 1 toFIG. 3, FIG. 5, and FIG. 6, the lock pin 16 is engaged with the engagingconcavity 19 by urging force from the coil spring 18 (lock pin engagingstate). From that state, when the hydraulic pressure is supplied to theengaging concavity 19 through the release oil passage 20 to pressurizethe lock pin tip 16 a, the lock pin 16 outwardly slides radially to thedevice within the lock pin receiving hole 15 against the urging forcefrom the coil spring 18, and is released from the engaging concavity 19.At that time, oil existing on the back pressure side of the lock pin isexhausted from a clearance provided between the lock pin receiving hole15 and the shaft 17. As shown in FIG. 7 and FIG. 8, as released from thelock pin 16, the rotor 10 can relatively rotate in the advanced-sidedirection as shown in FIG. 4 in such a manner that the advanced-side oilpressure chamber 11 is supplied inside with oil through theadvanced-side oil passage 13 and oil existing in the retarded-side oilpressure chamber 12 is exhausted through the retarded-side oil passage14.

On the other hand, when the relative position of the rotor 10 withrespect to the case 4 is at an advanced position, the retarded-side oilpressure chamber 12 is supplied with oil through the retarded-side oilpassage 14 and oil existing in the advanced-side oil pressure chamber 11is exhausted through the advanced-side oil passage 13; thus, the rotorrotates relatively in the retarded-side direction. When the relativeposition of the rotor 10 with respect to the case 4 rotates to the mostretarded position, the lock pin 16 inwardly slides radially theretowithin the lock pin receiving hole 15 by urging force from the coilspring 18, and engages with the engaging concavity 19.

As mentioned above, according to the first embodiment, it is arrangedsuch that the hole having a diameter approximating to the diameter ofthe receiving hole receiving the lock pin and the coil spring is formedthrough the shoe with intersecting the receiving hole, and is insertedthe substantially cylindrical shaft into the hole, to thereby lock thecoil spring against dashing out movement. This enables the hole to beinserted by the shaft to be manufactured in a large diameter by dieing,and also enables the hole to be formed at one time when the case ismanufactured by forging or the like. Therefore, the hole-opening processby machining is eliminated, which achieves reduced manufacturing costthereof. It should be noted that since a substantially cylindrical orsimple shaped one can be employed for the above shaft, it can bemanufactured at one time by forging or the like without any-machiningprocesses. As a result, the production cost can be reduced, looseneddimensional accuracy can be achieved, and further workability andassembling can be improved.

Second Embodiment

FIG. 9 is a traverse sectional view of essential parts showing thesecond embodiment. It is arranged such that the diameter of the shaft 17is smaller than the diameter of the lock pin receiving hole and thediameter of the coil spring 18. Such arrangement of the device enablesthe coil spring 18 to be inwardly compressed radially to the device byusing a U-shaped assembly tool 21, having a forked piece 21 a passingthrough a clearance 22 formed between the lock pin receiving hole 15 andthe shaft 17. As a result, the shaft 17 can be easily inserted into thehole 4 b-1, which is formed axially to the device, thereby performingimproved assembling capacity. It will be appreciated that aftercompletion of the assembly, when the assembly tool 21 is detachedtherefrom, the clearance 22 provided between the lock pin receiving hole15 and the shaft 17 serves as a drain hole or a drain groove forexhausting oil to the back pressure side of the lock pin.

Third Embodiment

As is shown for example in the drawings, the shaft 17 is designed, e.g.,in a D-shaped cross section so as to have at least one plane bearingsurface 17 a receiving the coil spring axially to the shaft on its outerperipheral surface. The dimensions thereof are designed such that, if acircular arc surface of the shaft 17 is opposed to the end face of thelock pin because of the wrong assembly direction of the shaft 17, theend face of the lock pin abuts against the circular arc face of theshaft 17 and thereby, the front end of the lock pin always projects fromthe inner periphery of the case 4 before the lock pin is completelyreceived in the receiving hole 15. Consequently, since as shown in FIG.11 the rotor 10 cannot be inserted in the direction indicated by thearrow, or as shown in FIG. 10 the rotor 10 cannot rotate, the assemblyproves to be improper, which enables the positive prevention of deliveryof incorrectly assembled products.

On the other hand, when the D-shaped plane section 17 a of the shaft 17is opposed to the end face of the lock pin 16, the D-shaped planesection 17 a of the shaft 17 compresses the coil spring 18 to make thelock pin 16 project from the receiving hole 15. However, since thedimensions are designed such that the lock pin 16 can be completelypushed into the receiving hole 15 before the end face of the lock pinabuts against the D-shaped plane section 17 a of the shaft 17, thedevice can normally operate.

Note that some inclination of the plane section 17 a of D-shape of theshaft 17 with respect to the sliding direction of the coil spring 18 iscorrected in such a manner that the shaft 17 is rotated within the shaftinserting hole because the bearing surface of the coil spring 18 or thelock pin 16 directly presses the shaft 17.

Fourth Embodiment

FIG. 8 is a view showing the fourth embodiment. On either or both of thefront cover 5 and the rear cover 6 against which the end of the shaft 17abuts (in FIG. 8, only on the front cover 5), a positioning concavity 5a engaged with the end of the shaft is formed. For instance, when theshaft 17 has a D-shaped cross section, this arrangement enables theprevention of incorrect assembly of the shaft 17 by forming thepositioning concavity 5 a also having a D-shaped cross section, andenables the prevention of rotation of the shaft 17 caused by vibrations.

Fifth Embodiment

FIG. 12 is a traverse sectional view of essential parts showing thefifth embodiment. The shaft 17 is designed in the shape of a cylinder,and the lock pin 16 is designed in the shape of a stepped cylinder. Thecoil spring 18 is provided around the small diameter section of the lockpin; one end of the bearing surface thereof abuts the circular arcsurface of the shaft 17, while the other end thereof abuts the steppedsection of the lock pin 16. Moreover, the end face of the small diametersection side of the lock pin 16 is caused to abut against the circulararc surface of the shaft at the time of release of the lock pin toprevent the coil spring from sticking.

Since such an arrangement enables the diameter of the coil spring to besubstantially the same as the diameter of the receiving hole, thereceiving hole 15 serves as a guide at the time of contraction andexpansion of the coil spring, and thereby, acts as a preventer againstinclination.

It should be noted that if the bearing surface of the coil spring 18abuts on a circular arc surface of the shaft 17 as in the case of thefifth embodiment, the bearing surface section of the coil spring may betwofold or threefold wound in order to prevent deformation of thebearing surface thereof.

INDUSTRIAL APPLICABILITY

As mentioned above, the present invention is able to be widely appliedto a valve timing adjusting device employing a locking member excellentin workability and assembling, installed in an engine and so on.

1. A valve timing adjusting device comprising: a first rotor thatintegrally secures a case inside having a plurality of projecting shoesand forming oil pressure chambers between those shoes, a front cover,and a rear cover, both covering the oil pressure chambers, and thatrotates integrally with a crank shaft; a second rotor that has aplurality of vanes each dividing each of the oil pressure chambers intoan advanced-side oil pressure chamber and a retarded-side oil pressurechamber, is able to relatively rotate by a predetermined angle withinthe first rotor, and is secured integrally with an intake or exhaustcamshaft; a hydraulic pressure supply and exhaust means capable ofsupplying working fluid to and exhausting it from the advanced-side oilpressure chambers and the retarded-side oil pressure chambers; a firsthole passing through the shoe radially to the device; a second holeformed through the shoe, intersecting the first hole; a coil springpressing a lock pin received in the first hole to thereby engage thelock pin into a concavity provided on an outer peripheral surface of thesecond rotor; and a shaft inserted into the second hole in order toprevent the coil spring from dashing out.
 2. The valve timing adjustingdevice according to claim 1, wherein the diameter of the shaft issmaller than the diameter of the first hole.
 3. The valve timingadjusting device according to claim 1, wherein the diameter of the shaftis smaller than the diameter of the coil spring.
 4. The valve timingadjusting device according to claim 1, wherein the shaft has a planebearing surface receiving the coil spring on a part of its outerperipheral surface.
 5. The valve timing adjusting device according toclaim 4, wherein the shaft has a D-shaped cross section.
 6. The valvetiming adjusting device according to claim 1, wherein a positioningconcavity is formed on either or both of the front cover and the rearcover on which the end of the shaft abuts.
 7. The valve timing adjustingdevice according to claim 1, wherein the shaft is at one time formed byforging.